Human voices are scarier for animals in African savannah than a lion’s growl

Mammals living in the African savannah are far more afraid of hearing a human voice than a lion’s growl, according to a new study that may lead to better strategies to steer animals away from poachers.

Mammals in South Africa’s Greater Kruger National Park, which is home to one of the world’s largest remaining lion populations, were assessed on how they reacted to the voices of other animals, said the research, published on Thursday in the journal Current Biology.

Scientists, including those from Western University in Canada, observed how 19 different mammal species reacted to a series of recordings, including human voices, lion vocalisations, barking dogs and gunshots.

The human-voice clips in the study were at conversational volume levels and came from radio or television recordings of people speaking languages in the region that included Tsonga, Northern Sotho, English and Afrikaans.

Sounds of dogs and gunshots were meant to represent human hunting and the lion vocalisations were meant to signal the presence of the top predator in the region, scientists said.

“Lions are the biggest group-hunting land predator on the planet, and thus ought to be the scariest, and so we’re comparing the fear of humans versus lions to find out if humans are scarier than the scariest non-human predator,” study co-author Michael Clinchy said.

“The key thing is that the lion vocalisations are of them snarling and growling, in ‘conversation’ as it were, not roaring at each other. That way the lion vocalisations are directly comparable to those of the humans speaking conversationally,” Dr Clinchy explained.

Researchers used custom waterproof systems that combined a camera trap and a speaker to capture recordings of all the animals coming to drink at waterholes in the park.

Analysing about 15,000 videos, scientists found that animals were twice as likely to run and abandon waterholes in response to hearing humans compared to hearing lions or hunting sounds.

About 95 per cent of species – including giraffes, leopards, hyenas, zebras, kudu, warthog, impala, elephants and rhinoceroses – ran more often or abandoned waterholes faster in response to humans than in response to lions, the study noted.

“There’s this idea that the animals are going to habituate to humans if they’re not hunted. But we’ve shown that this isn’t the case,” Dr Clinchy said.

“The fear of humans is ingrained and pervasive, so this is something that we need to start thinking about seriously for conservation purposes,” he said.

Researchers are exploring whether the findings can be used to deliberately steer endangered species such as the Southern white rhino away from known poaching areas in South Africa.

“I think the pervasiveness of the fear throughout the savannah mammal community is a real testament to the environmental impact that humans have,” said Liana Zanette, another author of the study.

“They are scared to death of humans, way more than any other predator,” Dr Zanette said.